1. Field of the Invention
The present invention relates to a method for treating an injured part on the oral mucosa, which comprises covering the injured part with a covering materials to be used for protecting the injured part from extrinsic irritations, and to said covering material.
More particularly, this invention relates to a method for treating an injured part on the oral mucosa, which comprises covering the injured part with a covering material which is characterised by covering the injured oral mucosa suffering from aphtha, wound, erosion, canker, etc. to protect the injured part from extrinsic irritations caused by the tongue, tooth, food, etc. for many hours by adhering to the injured part on the oral mucosa while it gradually becomes swollen and soft upon absorbing saliva or secretion, and to said covering material.
2. Description of the Prior Art
In the past, almost nothing has been known as a covering material to protect an oral mucosa injury such as aphtha, etc. from extrinsic irritations, except for some ointment bases such as petrolatum, etc. applied to such purpose. However, such ointment bases as petrolatum, etc. are unsatisfactory as a covering material to protect the injured part on the oral mucosa from extrinsic irritations in view of the fact that, having no adhesion to the injured mucous membrane, they would come off or run down and that they make the patient unpleasant by filling the mouth with unctuous materials.
Japanese Laid-Open Patent Publication No. 38412/76 discloses a buccal preparation composed of a medicament, an excipient (i.e., crystalline cellulose, mannitol, lactose, surbitol, anhydrous calcium phosphate, amylose), and a sodium salt of polyacrylate having a property to adhere to a diseased part in the oral cavity and also a property to swell; however, a study conducted by the present inventors points to a conclusion that the preparation consisting of a sodium salt of polyacrylate, excipient, and medicament does not always serve satisfactorily as a covering material for the injured oral mucosa, since it often fails to show enough adhesion, swells too much taking an irregular shape and makes the patient feel uncomfortable, tastes bad, stimulates the secretion of saliva, and is apt to drop off or run down.
On the other hand, Japanese Laid-Open Patent Publication No. 41320/79 discloses a show-releasing medical preparation to be administered by adhering to the oral mucosa comprising hydroxypropyl cellulose, polyacrylic acid or its pharmaceutically acceptable salt, and a medicament. Japanese Laid-Open Patent Publication No. 62012/80 discloses a slow-releasing medical preparation to be administered by adhering to a wet mucosa surface comprising an adhesive layer composed of a polymer which has the adhesiveness to a wet mucosa surface (i.e., hydroxypropyl cellulose, polyacrylic acid or its pharmaceutically acceptable salt) and a nonadhesive layer composed of lactose, starch, etc. and at least either one of said adhesive layer and nonadhesive layer is made to contain a medicament.
However, in the two Japanese patent document cited above, it is not at all disclosed and suggested that the preparation consisting essentially of a cellulose lower alkyl ether and a polyacrylic acid or its pharmaceutically acceptable salt and not containing a medicament can be used to cover the injured part on the oral mucosa and has an ability enough to cure the injured part suffering from aphtha, wound, erosion, etc.